Deathjack is your Major threat. He marches up the board, looking angrily at anything coming his way. Hes followed by the full unit of Bane Thralls, who are all stealthed (hard to hit with ranged/magic) The Bane Thralls are supported by Tartarus and Gerlak, who can charge through/around the Bane Thralls to get to bad guys.

The Cankerworm flanks. This is highly important. 2 things will happen - the enemy sends far more points than the Cankerworm is worth to go kill it, or he doesnt and the Cankerworm assassinates their caster/something really important.

The Scrappys flank the other direction. Scrappys explode when they die and when they attack so are like suicide bombers. Great against troops.

The Necrotech, Nightwretch, Skarlock and Gaspy form the squishy center of your formation. The most important models, and the support models. Use the Skarlock and Nightwretch forward to keep Gaspy safe, and fling spells at enemys or buff up your troops when needed.

The Cankerworm should flank on the flank of the enemies with their biggest warjack/warbeast. the Scrappys should flank on the flank of the enemies with their troops, or power-solos. You can mix and match, chuck 2 scrappys with canker and the remaining 5 on the other flank.